Exam2Lec4Neisseria, Haemophilus, & Anaerobes Flashcards
What is the morphology of the genus Neisseria ?
Gram negative cocci
What are the two important species of neisseria?
Gonorrhoeae
meningitidis
Where is neisseria found?
around and inside of neutrophils
What is the spectrum of the disease (neisseria)?
Systemic, life-threatening disease
neisseria meingococci is found where?
Upper respiratory tract
neisseria gonococci is found where?
Genital tract
Details of neisseria species
gram negative, non-motile encapsulated, diplococcus, kidney shaped
aerobic but can grow without oxygen as a facultative anaerobe
fastidious growth
What media does neisseria species grow on? and for how long?
modified Thayer-martin medium or chocolate agar for 48 hours
What is the host of neisseria meningitidis ?
humans are the only natural hosts
What is the portal of entry of neisseria meningitidis?
nasopharynx
What are 3 major factors/ virulence factors of n. meningitidis?
Pili: colonization of nasopharynx–> become transient flora
Capsule–>systemic spread: bacteremia and meningitis
lps/los
No Man Picks Chick Last
What are the diseases of neisseria meningitidis ?
SPAMS Baby Daddy
Purpura fulminans
Meningitis
Septicemia
bacteremia
Arthritis
Shock
Death
What causes systemic spread of neisseria meningitidis ?
capsule
How can we classify N. meningitidis ?
Serogroups
–polysaccharide capsule: A,B, C, Y, W-135
What is the importance of serogroups of N.meningitdis?
Relation to disease:
-certain serogroups relate to disease
-public health tracking of outbreaks
-Development of vaccines
Protection of N.meningitidis requires what?
antibodies and complement
What is the N.meningitidis vaccine?
-Groups A,C, Y and W-135 polysaccharide conjugated to protein carrier (diphtheria toxoid Menactra®)
-Recommended for all 11-12 year olds, others based on risk factors
-Separate group B vaccine
What is the age recommendation for n.meningitdis vaccine?
11-12 years old
Clinical case :
- 3 year old baby is taken to the ER -fever & lethargy for 1 day, petechial rash & purpuric lesions, listless
- Blood cultures, IV antibiotics, hospital
- Lumbar puncture - CSF – white blood cells, (94% PMNs)
- Blood cultures positive for Gram negative diplococci,
N. meningitdis
What is the treatment of N.meningitis
antibiotics: penicillin, third generation cephalosporin (vefotazime, ceftriaxonr)
MEDICAL EMERGENCY
What is the symptoms of N. Meningitis?
Stiff neck
petechial rash
purpuric lesions
WBC in CSP
Gram negative diplococci in blood
What are the virulence factors of N. gonorrhoeae?
CROP LIP
Pili: responsible for attachment to host epithet cells
IgA protease: cleaves IgA molecule
Capsule
OPA: assist piling attachment
LOS: endotoxin activity
Por proteins: forms pores through outer membrane
Rmp proteins: inhibits cidal activity of serum
What are the surface factors of N. gonorrhoeae ?
Pili
IGA protease
Capsule
Opa
LOS
Role of pili in N. gonorrhoeae
Responsible for attachment to host epithelial cells
Role of IgA protease in N. gonorrhoeae
Cleaves IgA molecule
role of capsule in N. gonorrhoeae
avoid phagocytosis
role of opa in N. gonorrhoeae
assist in pili in attachment
role of LOS in N. gonorrhoeae
Endotoxin activity
Why is neisseria gonorrhoeae such a successful pathogen
antigenic variation
Example antigenic variation
Multiple copies (10-15) of pilin gene
Recombination (splicing) of one of the copies of the pilin gene (pilS) with the control regions (pilE)
Recombination within PilS
What is the clinical presentation of N. gonorrhoeae ?
Urethritis
Cervicitis
Salpingitis
proctitis
Pharyngitis
Arthritis
conjunctivitis
PID
Septicemia
What is the reservoir for N. gonorrhoeae
humans only reservoir-asymptomatic carrier
Who is at the highest risk for n. gon?
Teens and young adults
What is the transmission of N. gonorrhoeae
Sexual contact primary
What is the clinical presentation in men of N. gonorrhoeae ?
-usually symptomatic
-2 to 7 days post infection:
urethral discharge “the drips”
dysuria
complications are rare
rectal and pharyngeal infections
Female or male have higher chance of complication of n. gonorrhea
female
Female or male are more symptomatic
males
What is the clinical presentation of n. gonorrhea in WOMEN?
-frequently mild or asymptomatic
-vaginal discharge, dysuria, abdominal pain
-complications are common (10-20% of cases)
-ascending genital infection causes salpingitis, and PID
-rectal and pharyngeal infections
Both male and females infected with N. gonorrhea can get?
rectal and pharyngeal infections
What is PID (N. gonorrhea)?
Pelvic inflammatory disease
Complication of untreated N. gonorrhea
painful and may require surgical drainage or in severe causes hysterectomy
What is DGI ( N. gonorrhea )?
Disseminated gonococcal infection
N. gonorrhea in cirulatory system
Commonly includes septic arthritis
What is opthhalmia neonatorum (N. gonorrhea)? IMP
conjuctivitis resulting from vaginal delivery with infected mother
prevented with eye drops
How do we diagnosis gonorrhea
Direct Gram stain - effective for urethral discharge in symptomatic men
Gram (-) diplococci
Culture on chocolate agar or selective media
Oxidase +
Utilization of glucose confirmatory
What is the oxidase result of n. gonorrhea
positive–> purplish
What is the oxidase result of n. gonorrhea
positive–> purplish
What is the treatment of n. gonorrhea?
3rd generation cephalosporin with azithromycin and doxycycline
penicillin resistance now common due to mutated PBP and plasmid encoded beta-lactamase
sexual contacts should be treated to prevent “ping pong” infections
What is n. gonorrhea resistant to
penicillin resistance now common due to mutated PBP and plasmid encoded beta-lactamase
n. gonorrhea can be prevented through what ?
education and safe sex
What is the morphology of haemophilus influenzae ?
Gram negative coccobacilli
Fastidious
H. influenzae can have strain that contain what?
may have polysaccharide capsule which determines serotype (a-f) -invasive disease
what version of H. influenzae is not as invasive
non-encapsulated
What are the virulence factors of H. influenzae
Capsule
Endotoxin
IgA protease
Pili for adherence
Where do non encapsulated varieties of H. influenzae colonize? where does it spread?
upper respiratory tract
spread locally- otitis media, sinusitis, bronchitis, pneumonia
What does non-encapsulated H.influenzae cause
otitis media, sinusitis, bronchitis, pneumonia
Where do we see encapsulated varieties of H.influenzae?
disease in unimmunized children
What do the cell wall components of encapsulated H.influenzae cause?
impair ciliary function-damage of respiratory epithelium, enter blood
Encapsulated H.influenzae causes what?
meningitis, epiglottis, cellulitis
What is the old H.influenzae vaccine?
polysaccharide vaccines
why do we not use H.influenzae polysaccharide vaccines ?
because there was not a good immune response
What is the new H.influenzae vaccine?
Conjugated vaccine
What are the symptoms of H. influenzae epiglottitis?
Cherry red swollen epiglottis
Fever
score throat
hoarseness
barking and cough
progresses rapidly into medical emergency
What is the treatment of H. influenzae epiglottitis
antibodies treatment (3rd generation of cephalosporin)
Airway maintenance needed
What is the carrier rates of H. influenzae?
as high as 80% in children
20-50% in adults
Humans only source
If there is a breakout of H. influenzae, what are people treating with?
Rifampin
Professor said when you see childcare/daycare to think of…
H. influenzae
Where is the energy derived from in anaerobic bacteria
fermentation
What is toxic to anaerobic bacteria
oxygen
Anaerobic bacteria are normal flora where?
oral cavity and GI tract
Anaerobic wound infection are often ____
polymicrobial
synergism
What is the morphology of clostridium
gramp positive rods-spore formers
Extra detail: Ubiquitous
Why clostridium can cause disease?
Spore formation
Some have rapid growth in nutritionally enriched, oxygen-deprived environments
Exotoxins
What is the morphology of C. perfringens?
Large rectangular gram positive rod
does C. perfringens grow fast or slow
fast
what are virulence factors of C. perfringens
Alpha-toxin
Beta toxin
Epsilon toxin
Iota toxin
ALL EXOTOXINS
C. perfringens’s exotoxins can act as ___
superantigens
Binds to outside of MHC Class II cleft to stimulate T cell activity
What is C. perfringens clinical disease?
Cellulitis: Swollen, red area of skin that feels hot and tender
Fasciitis: Inflammation of connective tissue
Myonecrosis: Localized death of muscle cell fibers
Food poisoning: most common
is C. perfringens always dangerous?
No: Colonize wounds with no clinical significance
BUT
—1 week after exposure can lead to intense pain, extensive muscle necrosis, shock, renal failure and death – within 2 days.
How do we diagnosis C. perfringens?
Culture for 1 day
some immunoassays
How do we treat C. perfringens skin infections?
Antibiotics – penicillin
Debridement
Hyperbaric oxygen
How do we treat C. perfringens food poisoning
maintain hydration
What is the morphology of c. tetani
Large, spore-forming rod
Terminal spores
extra detail: Ubiquitous
Is C. tetani easy or hard to grow ?
hard- very sensitive to oxygen
What are the virulence factors of C. tetani
Spores
2 toxins:
Tetanolyisin
Tetanospasmin
What is tetanolysin in C. tetani
toxin
oxygen labile hemolysis
What is tetanospasmin in C. tetani ⭐️
Oxygen-labile neurotoxin
Produced during stationary growth phase
Responsible for the clinical manifestations of tetanus, spastic and rigid paralysis
What does the tetanospasmin do in C. tetani?⭐️
blocks the release of inhibitor transmitters (ex.GABA) so if we block this we will have constant excitatory transmitters
TOXIN BINDING IS IRREVERSIBLE
tetanus disease relate to ____
to distance of wound from the CNS
What is generalized tetanus ? ⭐️
Most common form
-Masseter muscles (trismus or lockjaw)
-Sustained contraction of the facial muscles is called risus sardonicus
-Drooling, sweating
What is localized tetanus
Disease confined to musculature at site of primary infection
Example is cephalic tetanus
What is neonatal tetanus
Infection of the umbilical stump
Developing countries
90% fatal
How do we diagnosis c. tetani
Confirmational
Tissue debridement
How do we treat c. tetani
Antibiotics – metronidazole
Passive immunization with human tetanus Ig
what preventive measures do we have for c. tetani
Vaccination (toxoid)
What is the morphology of C. botulinum
Large Gram positive spore forming rod
What is the morphology of C. botulinum
Large Gram positive spore forming rod
what is the virulence factor of C. botulinum ?
botulinum toxin
what does the botulinum toxin result in? ⭐️
Result is flaccid paralysis
how does the botulinum toxin work?
Large progenitor protein (A-B toxin)
Complexed with non-toxic proteins – protects in digestive tract
Heavy chain binds sialic acid receptors and glycoproteins on motor neuron surfaces and stimulates endocytosis of the toxin
Botulinum neurotoxin remains at the neuromuscular junction
Inactivation of proteins regulating release of acetylcholine, blocking neurotransmission at peripheral cholinergic synapses
what are the clinical diseases of c. botulism
Classic or food borne
infant
wound
inhalation
What causes food borne botulism
Home canning - one taste leads to disease – eating toxin
Usually an intoxication
What are the symptoms of food borne botulism
Blurred vision, dry mouth, abdominal pain
Bilateral descending weakness – flacid paralysis
what causes infant botulism
infection of spores
consumption of honey with spores then they germinate
What is the treatment of c. botulinum
Ventilatory support
Use of trivalent botulinum antitoxin
Antibiotics for wound infection
C. difficile is considered what?
antibiotic-associated GI diseases
-Treat with antibiotics – kills some normal flora
-Result can be an overgrowth of Clostridium difficile
——-Benign, self-limited diarrhea
——-Severe, life-threatening pseudo-membranous colitis
The benign version of C.difficile causes what?
self limited diarrhea
The severe version of C.difficile causes what?
life-threatening pseudo-membranous colitis
What are the two toxin in C.difficile?
Enterotoxin (Toxin A)
—–Chemotactic for neutrophils
—-Cytopathic effect – disrupts tight cell-cell junctions, leading to greater permeability of the intestinal wall and diarrhea
Cytotoxin (Toxin B)
—–Actin depolymerization - destruction of the cellular cytoskeleton
Toxin A of C.difficle is what
enterotoxin
Chemotactic for neutrophils
Cytopathic effect – disrupts tight cell-cell junctions, leading to greater permeability of the intestinal wall and diarrhea
Toxin B of C. difficile is what
cytotoxin
Actin depolymerization - destruction of the cellular cytoskeleton
What percentage of people have c.diff as normal flora
5% but higher in hospitalized patients
How is c.diff diagnosis is confirmed by____
by enterotoxin or cytotoxin detection
What is the morphology of c.diff
Anaerobic Gram+ spore-forming bacillus
What does C.diff cause?
Clostridium difficile-associated disease (CDAD)
Pseudomembranous colitis, toxic megacolon, sepsis, and death
what is the C.diff transmission
Fecal-oral transmission through contaminated environment and hands of healthcare personnel
What is a major risk factor for disease with c.diff
Antimicrobial exposure
Acquisition and growth of C. difficile
Suppression of normal flora of the colon
What is the mutant of c.diff in health care facilities?
NAP1 mutant
-Increased toxin production
-Produces new toxin
-Also causes community associated diarrhea
How is c.diff diagnosis ?
Isolation of bacterium from stool by anaerobic culture
Identification of toxin from stool
How is C.diff treated?
Discontinue antibiotic therapy
Vancomycin or metronidazole for severe disease
Bacteriotherapy aka fecal transplant
Clinical example:
An 80-year-old woman was treated for a UTI with ampicillin. Several days later she developed fever and diarrhea. The stool sample was positive for the toxin associated with which of the following bacteria?
A.Clostridium botulinum
B. Neisseria meningitidis
C. Clostridium difficile
D. Haemophilus influenzae
E. Staphylococcus aureus
C
A 5-year-old boy wakes his parents in the middle of the night. He had a high fever (40C) and shortness of breath. The child was brought to the hospital and an X-ray of the lateral neck revealed swelling of the epiglottis. Which of the following bacteria is MOST LIKELY to be the etiological agent of his illness?
a.Haemophilus influenzae
b. Streptococcus pneumoniae
c. Streptococcus pyogenes
d. Neisseria meningitidis
e. Clostridium tetani
a
Which one of the following is NOT an important characteristic
of either Neisseria gonorrhoeae or Neisseria meningitidis?
(A) Polysaccharide capsule
(B) IgA protease
(C) M protein
(D) Pili
c
Three organisms, Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae, cause the vast majority of cases of bacterial meningitis. What is the MOST important pathogenic
component they share?
(A) Protein A
(B) Capsule
(C) Endotoxin
(D) β-Lactamase
b
Each of the following statements concerning Clostridium
perfringens is correct EXCEPT:
(A) It causes gas gangrene.
(B) It causes food poisoning.
(C) It produces an exotoxin that degrades lecithin and causes
necrosis and hemolysis.
(D) It is a gram-negative rod that does not ferment lactose.
d
Each of the following statements concerning Clostridium tetani
is correct EXCEPT:
(A) It is a gram-positive, spore-forming rod.
(B) Pathogenesis is due to the production of an exotoxin that
blocks inhibitory neurotransmitters.
(C) It is a facultative organism; it will grow on a blood agar plate
in the presence of room air.
(D) Its natural habitat is primarily the soil.
c
Each of the following statements concerning gonorrhea is correct EXCEPT:
(A) Infection in men is more frequently symptomatic than in
women.
(B) A presumptive diagnosis can be made by finding gram-
negative kidney bean-shaped diplococci within neutrophils in a urethral discharge.
(C) The definitive diagnosis can be made by detecting antibodies
to Neisseria gonorrhoeae in the patient’s serum.
(D) Gonococcal conjunctivitis of the newborn rarely occurs in
the United States, because silver nitrate or erythromycin is
commonly used as prophylaxis.
c
Each of the following statements concerning neisseriae is correct EXCEPT:
(A) They are gram-negative diplococci.
(B) They produce IgA protease as a virulence factor.
(C) They are oxidase-positive.
(D) They grow best under anaerobic conditions.
d
Each of the following statements concerning wound infections
caused by Clostridium perfringens is correct EXCEPT:
(A) An exotoxin plays a role in pathogenesis.
(B) Gram-positive rods are found in the exudate.
(C) The organism grows only in human cell culture.
(D) Anaerobic culture of the wound site should be ordered.
c
Each of the following statements concerning Neisseria
meningitidis is correct EXCEPT:
(A) It is an oxidase-positive, gram-negative diplococcus.
(B) It contains endotoxin in its cell wall.
(C) It produces an exotoxin that stimulates adenylate cyclase.
(D) It has a polysaccharide capsule that is antiphagocytic.
c
CASE: Your patient is a 20-year-old woman with the sudden onset of fever to 104°F and a severe headache. Physical examination reveals nuchal rigidity. You suspect meningitis and do a spinal tap. Gram stain
of the spinal fluid reveals many neutrophils and many gram-negative diplococci. Of the following bacteria, which one is MOST likely to be the
cause?
(A) Haemophilus influenzae
(B) Neisseria meningitidis
(C) Streptococcus pneumoniae
(D) Pseudomonas aeruginosa
b
CASE: Your patient is a 70-year-old man with a long history of smoking who now has a fever and a cough productive of greenish sputum. You suspect pneumonia, and a chest X-ray confirms your suspicion.
596. If a Gram stain of the sputum reveals very small gram-negative rods and there is no growth on a blood agar but colonies do grow on chocolate agar supplemented with NAD and heme, which one of the following bacteria is the MOST likely cause?
(A) Chlamydia pneumoniae
(B) Legionella pneumophila
(C) Mycoplasma pneumoniae
(D) Haemophilus influenzae
d
CASE: Your patient is a 70-year-old man with a fever of 40°C and a
very painful cellulitis of the right buttock. The skin appears necrotic, and there are several fluid-filled bullae. Crepitus can be felt, indicating gas in the tissue. A Gram stain of the exudate reveals large gram positive rods. Of the following, which one is the MOST likely cause?
(A) Clostridium perfringens
(B) Bacillus anthracis
(C) Corynebacterium diphtheriae
(D) Actinomyces israelii
a
